Make `spark.home` and `spark.kubernetes.file.upload.path` configurable.

[sudiptob2]

InsubmitArmadaSpark.sh script,

Currently /opt/spark and /opt/spark/bin/spark-submit are hard-coded. These paths should be configurable.
SPARK_HOME should be used to locate Spark binaries, falling back to /opt/spark if not set (e.g., ${SPARK_HOME:-/opt/spark}).

Similarly for --conf spark.kubernetes.file.upload.path=/tmp